“However, spare batteries, including power banks, are not permitted to be carried in check-in bags. They are permitted in hand- carry bags only.”

Singapore carriers also have their own guidelines, on top of what is now required by the regulator.

On Jetstar Asia flights, those who wish to carry the items onboard are allowed two lithium-ion batteries under 101 watt-hours each that are part of electronic equipment.

Only one other spare battery under 101 watt-hours may be carried on board, said a spokesman.

On Tigerair, passengers may carry on board personal devices with a capacity of up to 160 watt-hours.

Singapore Airlines allows laptops and mobile phones with less than 100 watt-hours and a lithium content of less than 2g as onboard items. A mobile phone typically uses a battery that is less than 10 watt-hours.

CAAS conducts regular audits and inspections to ensure guidelines are adhered to, said a spokesman.